Method for nanomaterials chemical deposition using pulsed laser

ABSTRACT

A method of selectively controlling materials structure in solution based chemical synthesis and deposition of materials by controlling input energy from pulsed energy source includes determining solution conditions, searching and/or determining energy barrier(s) of a desired materials structure formation, applying precursor solution with selected solution condition onto a substrate, and applying determined input energy from a pulsed energy source with a selected condition to the substrate, thereby nucleating and growing the crystal.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation-in-part application which isrelated to and claims the priority benefit of U.S. Non-Provisionalpatent application Ser. No. 16/600,650 filed 14 Oct. 2019, the contentsof which are incorporated herein by reference into the presentdisclosure.

STATEMENT REGARDING GOVERNMENT FUNDING

This invention was made with government support under CMMI 1663214awarded by the National Science Foundation. The government has certainrights in the invention.

TECHNICAL FIELD

The present disclosure generally relates to processes for manufacture ofnano-scale and micro-scale structured materials, and more particularly,to processes of controlling crystal nucleation and growth.

BACKGROUND

This section introduces aspects that may help facilitate a betterunderstanding of the disclosure. Accordingly, these statements are to beread in this light and are not to be understood as admissions about whatis or is not prior art.

Nanomaterials synthesis with selective attributes and particularlycrystal synthesis with morphologies of interest are commonplacenowadays. For example, desired size, orientation, crystallizationstructure on substrates are all attributes of crystal growth anddeposition that skilled artisans seek to manipulate.

In conventional materials synthesis methods, chemical processes arewidely used to control crystal growth, such as adjusting pH values ofintermediate solutions, adding capping agents, etc., known to a personhaving ordinary skill in the art. However, these methods suffer from lowsynthesis efficiency. This low efficiency results from intrinsicfeatures such as low production rate and or synthesis processes that caneasily stray out of control, for example, slightly different pHenvironment can lead to nanomaterials product with dramaticallydifferent morphologies. Moreover, current nanomanufacturing processesinvolve multiple steps to create nanomaterials with desired morphologyto meet various design specifications that is both time consuming andcostly.

Therefore, there is an unmet need for a novel approach for nano-scaledcrystal synthesis including crystal nucleation as well as crystal growththat does not suffer from the aforementioned shortcomings of the priorart.

SUMMARY

A method of selectively controlling nucleation for crystalline formationincludes determining minimum energy barriers of a desired crystalformation by stepped increasing the pulsed laser condition. The methodincludes applying the selected precursor solution having a selectedcondition on to substrate. Furthermore, the method includes applyingpulsed laser as an pulsed energy source with predetermined input energyat least at the minimum energy barrier to the substrate, therebynucleating the crystal. The selected input energy of the pulsed laser isdefined by a laser condition of any combination of the followingsetting: laser energy (fluence), laser irradiation area, repetitionrate, pulse width (or duration per pulse), and total time of pulsationsof this condition.

Another method for selectively growing crystals is also disclosed. Themethod includes applying the selected precursor solution having aselected condition on to the pre-nucleated substrate. Then the methodincludes determining the minimum energy for a desired crystal growth andthe maximum energy of growing crystals without additional nucleation, bystepped increasing the pulsed laser condition. The determined inputenergy of the pulsed laser is defined by a laser condition of anycombination of the following setting: laser fluence, laser irradiationarea, repetition rate, pulse width (or duration per pulse), and totaltime of pulsations. In addition, the method includes applying thedetermined input energy from a pulsed laser to a nucleated crystallinecompound provided on a substrate for a predetermined amount of time. Thecrystal growth is controlled i) kinetically, or ii) thermodynamically.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of Gibbs free energy vs. radius of nucleation,showing graphs of interface free energy, ΔG, and bulk free energy.

FIG. 2a is a graph of Gibbs free energy vs. radius in precursor solutionwith different concentration C.

FIG. 2b is a graph of Gibbs free energy vs. radius for crystals withdifferent surface energy, γ.

FIG. 3 is a graph of seed diameter in nm (nucleation) vs. laser powerdensity in kW/cm² and precursor solution condition (precursorconcentration in mM).

FIGS. 4a, 4b, and 4c are scanning electron microscopy (SEM) images ofnucleation (left) and corresponding crystal growth (right) under laserirradiation of 0.5 mJ/pulse (FIG. 4a ), 0.25 mJ/pulse (FIG. 4b ), and0.1 mJ/pulse (FIG. 4c ), all scale bars representing 1 μm in length.

FIG. 4d is a schematic diagram of heterogeneous nucleation in (0001)plane with contact angle θ=90° and in {0110} planes with θ=120°.

FIGS. 5a, 5b, 5c, and 5d are SEM images of grown ZnO crystal using themethods of the present disclosure, grown under laser power density ofabout 9.55 kW/cm² (FIG. 5a ), about 15.92 kW/cm² (FIG. 5b ), about 22.29kW/cm² (FIG. 5c ) and about 28.66 kW/cm² (FIG. 5d ) all at about 200 kHzfor about 5 min, with scale bars representing 500 nm in length.

FIG. 5e is a schematic of crystal growth in kinetic controlled andthermodynamic controlled processes (as marked in the correspondingpanels).

FIG. 6a is a sequence of SEM cross-sections images of nanorod crystalsgrown under power density from about 9.55 to about 28.66 kW/cm² at about200 kHz for about 5 mins, with all scale bars representing 2 μm.

FIG. 6b provides graphs of length in nm and aspect ratio of nanorodcrystals vs. power density in kW/cm².

FIG. 7a is an SEM image of ZnO crystals with (0001) face up deposited onsilicon substrate with an amorphous SiO₂ layer.

FIG. 7b is an SEM image of deposited ZnO crystals with a majority of thecrystal in (0001) face up free-standing on silicon substrate.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the embodimentsillustrated in the drawings, and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of this disclosure is thereby intended.

In the present disclosure, the term “about” can allow for a degree ofvariability in a value or range, for example, within 10%, within 5%, orwithin 1% of a stated value or of a stated limit of a range.

In the present disclosure, the term “substantially” can allow for adegree of variability in a value or range, for example, within 90%,within 95%, or within 99% of a stated value or of a stated limit of arange.

A novel approach for nano-scaled crystal synthesis including crystalnucleation as well as crystal growth is presented that does not sufferfrom the aforementioned shortcomings of the prior art. The presentdisclosure presented use of a controllable pulsed energy source such asa pulsed laser that controls material deposition in a precise manner.The present disclosure covers the ideas of using pulsed laser as a toolfor controlled delivery of specific energy density per unity of arearequired for achieving needed nucleation conditions and growthconditions respectively. Continuous wave laser may be used with addedcontrols. The present disclosure presented use pulsed laser thatcontrols materials produced by on-site synthesis and deposition based onfour prongs. Firstly, pulsed laser provides input energy with highprecision, therefore, the driving force of crystal nucleation and growthis controlled in precise quantitative manners. Secondly, since pulsedlaser inputs large dose of energy during a short period of irradiationtime; accordingly, thermodynamic and kinetic states of deposition alter,which generate novel reaction pathways. Thirdly, pulsed-laser is aprecise tool with high resolution that provide spatial and temporalcontrol. Thereby, pulsed-laser provides selective change in thedeposition condition in a localized region. Lastly, the controlledmethod by pulsed laser for nanomaterials deposition is throughthermodynamic and kinetic pathways, which can realize both catalytic andcatalyst-free processes during nucleation and crystal growth.

To these ends, the present disclosure provides a controlled synthesismethod to control materials structure by pulsed laser induced chemicaldeposition. In the synthesis, pulsed laser conditions are selected toadjust input energy then to control both initial crystal seeds in thenucleation process and crystal growth followed the nucleation process.The method of the present disclosure provides controlling materialsstructure which include providing a solution in a specific pH value andcomprising precursor reactants which could be below saturated condition.The present disclosure also teaches how to select different laserconditions to achieve an input energy for the desired materialsstructure. The materials structure includes crystal size in threedimensions, density, crystalline structure, crystal orientation, and theshape of the crystal product. The present disclosure also teaches how tocontrol synthesis process in the initial nucleation step and the crystalgrowth thereafter. In nucleation step, adjusting input energy of pulsedlaser to overcome the lowest energy barriers for nucleation leads toheterogenous nucleation with uniform crystal orientation. In crystalgrowth steps, adjusting input energy of pulsed laser tunes the crystalgrowth kinetics (growth rate) and leads to different materialmorphologies. A particular input energy of pulsed laser is determined bya laser condition of a combination of laser fluence, irradiation area,repetition rate, width (duration) of a pulse, and total time (or totalnumber of pulses).

Therefore, as discussed above, pulsed laser is used to selectivelyovercome the energy barriers for chemical deposition to initiatereaction for a certain morphology in a selected region. The method ofcontrol by pulsed laser applies to both the initial crystal formation innucleation process and in crystal growth followed.

In classical nucleation theory, when a crystal is initially formed itcould be regarded as a droplet. The Gibbs free energy ΔG of a droplet(assuming in spherical shape) is described as in following:

-   where ΔG_(ν) is the bulk energy,

${\Delta \; G} = {{\frac{3}{4}\pi \; r^{3}\Delta \; G_{v}} + {4\mspace{14mu} \pi \; r^{2}\gamma}}$

-   γ is the surface energy also referred to as the resistance force for    nucleation, and-   r is the radius of the droplet. ΔG_(ν) is often referred to as the    driving force of nucleation. The difference in bulk free energy    between product and reactant is related to saturation of solution    which is expressed as:

${\Delta \; G_{v}} = {{kT}\mspace{14mu} \ln \mspace{14mu} \frac{C}{C_{0}}}$

-   where C is the concentration of a solution,-   C₀ is the concentration of a solution when it is saturated,-   k is the Bolzmann constant, and-   T is temperature.

The Gibbs free energy change with crystal radius is shown in FIG. 1.Referring to FIG. 1, a diagram of Gibbs free energy is provided vs.radius of nucleation, showing graphs of interface free energy, γ, theGibbs free energy, ΔG, and bulk free energy, ΔG_(ν). The maximum valueof free energy is the energy barriers for nucleation ΔG*, when

$\frac{dG}{dr} = 0.$

Correspondingly, the value of r* at the energy barrier is the criticalsize of nucleation, after which addition of new molecules to nucleidecreases the free energy, so nucleation is more probable.

Effects of precursor concentration, C, and nuclei morphologies withdifferent surface energy γ, on the Gibbs free energy for nucleation isshowing in FIGS. 2a and 2b . Increase in the precursor concentrationwill lower the energy barrier height and therefore reduce the criticalsize. As shown in FIG. 2a , supposing that precursor concentrationC₁>C₂>C₃, which will lead to the corresponding critical size are r₁, r₂,and r₃, where r₁<r₂<r₃. As to crystals with different morphologies, theshape with lowest surface energy will have lowest energy barriers, ifthe concentration of solution is kept the same. As shown in FIG. 2b ,supposing that total surface energies of three different shape followthe sequence of γ₁>γ₂>γ₃, the corresponding energy barriers will beΔG₁>ΔG₂>ΔG₃.

By changing the precursor concentration, the critical size fornucleation can be selectively chosen. Specifically, higher concentrationwill lead to smaller initial crystal size, and lower concentration willlead to larger initial crystal size. Also, as shown in FIG. 2a , lowerconcentration leads to increase in energy barrier height. This attributecan be used to adjusting laser input energy. Specifically, with laserinduced chemical deposition, different energy barriers can be overcomeby adjusting laser input energy. Therefore, in condition with lowerconcentration level, initial crystals will have large size and a largerpulsed laser energy is needed.

Furthermore, different crystal planes have different surface energy, asinitial crystals have different levels of total surface energy andenergy barriers. The energy diagram is shown in FIG. 2b . Adjustinglaser energy to overcome different level of energy barriers, initialcrystals will have different morphologies, and morphologies of initialcrystals determine the morphology of the product.

To better illustrate the methodology of the present disclosure, ZnOcrystal formation is used as an example. A precursor solution wasapplied on silicon substrate by immersing substrate in precursorsolution, which contains precursor reactants of zinc chloride tohexamethylene tetramine (HMTA) in content ratio of 1:1. Steppedincreasing laser input energy by increasing laser power density untilthe deposition spot could be observed, then the laser input energy isregarded as just overcoming the lowest energy barrier for nucleation.Initial crystals with different materials structure is shown in FIG. 3,showing a graph of crystals in nucleation diameter in nm is provided vs.laser power density in kW/cm², and with precursor solution in differentlevel of concentration. Different morphologies are shown for eachcorresponding power and seed diameter. Increasing the laser powerdensity, changes the initial crystal morphology from sphere to hexagonalprism, and crystal size increase with precursor concentration decreaseand laser power increase accordingly. In FIG. 3, all scales represent 2μm in length.

Having discussed size of nucleation, orientation of the nucleation isnow discussed. Orientation of initial crystals are controlled innucleation step by laser induced chemical deposition, without the needof pre-deposition of seed layer or specific crystal structure ofsubstrates. Orientation of initial crystals determine the finalnanomaterials orientation as the crystals are grown. According to theclassical nucleation theory, the energy barriers ΔG_(hom) of homogenousnucleation is described by

${\Delta \; G_{\hom}} = \frac{16{\pi\gamma}^{3}}{3( {\Delta \; G_{v}} )^{2}}$

The energy barriers for heterogeneous nucleation are

ΔG _(het) =ΔG _(hom) f(θ)

which is smaller than homogeneous nucleation due to the structure factorf(θ). f(θ) is provided as follows:

f(θ)=(2−3 cos θ+cos³θ)/4

where θ is the constant angle between nuclei and substrate, as shown inFIG. 4d , discussed further below.

Referring to FIGS. 4a, 4b, and 4c , scanning electron microscopy (SEM)images of nucleation (left) and corresponding crystal growth (right)under laser irradiation of 0.5 mJ/pulse (FIG. 4a ), 0.25 mJ/pulse (FIG.4b ), and 0.1 mJ/pulse (FIG. 4c ) are provided, in which the laser beamsize is 200 μm. Referring to FIG. 4d , a schematic diagram ofheterogeneous nucleation in (0001) plane with contact angle θ=90° and in{0110} planes with θ=120° are shown. As before, the present disclosureis exemplified with ZnO crystals. Heterogeneously nucleated with (0001)facet contacting with substrate, the structure factor would bef(θ)=f)(90°=0.5. If it is nucleated with (0110) surface, the contactangle would be 120° and energy barrier would be 0.843 ΔG_(hom). So theenergy barriers under different conditions will have the relationship ofΔG_(nom)>ΔG_(het_random)>ΔG_(het_(0001)). The experimental results arecorresponding to the classical nucleation theory. By adjusting the laserinput energy just above the minimum energy barriers ΔG_(het_(0001)),which corresponding to the heterogeneous nucleation with (0001) planesattaching to the substrate, nanorod (the final product in this case)with orientation of [0001] perpendicular to the substrate are obtained.

With reference back to FIGS. 4a, 4b, and 4c , all scale bars represent 1μm in length. By changing the input energy in a step of 0.05 mJ/pulse,the energy barriers of different nucleation processes could bedetermined. It was observed in our experiment that large input energy of0.5 mJ/pulse will lead to homogeneous nucleation, and the crystal grownfrom the homogeneous nuclei will be randomly oriented, as shown in FIG.4a . Decreasing the laser power to 0.25 mJ/pulse, nucleation willtransfer from homogeneous to heterogeneous way. Only single layer ofcrystals formed on the substrate surface but without orientationpreference shown, so the crystals growth afterwards was also in singlelayer but randomly oriented (as shown in FIG. 4b ). If the laser powerdecreased to the level just above the threshold of nucleation, belowwhich nucleation will not be triggered, as 0.1 mJ/pulse determined inthe experiments according to the present disclosure, most nuclei havetheir c-axis ([0001] direction) perpendicular to the substrates, and thecorresponding NWs have up-straight orientation (as shown in FIG. 4c ).

Once the initial crystal is formed, the crystal is then selectivelygrown under these conditions. According to the present disclosure, usinga pulsed-laser methodology, crystal morphology is controlled in a moreprecise manner. Actual reduction to practice results showed that aspecific crystal structure occurs only if a certain input energy levelwas reached by laser. By selectively setting the laser power, thecrystal will grow with a desired morphology. Using ZnO crystals asexample, when the input power is below about 9.55 kW/cm², all crystalsurfaces were activated in a very low rate, and the crystal wouldundergo a homogenous growth and result in a spherical structure.Reference is made to FIGS. 5a, 5b, 5c, and 5d where SEM images of ZnOcrystal growth are shown. Specifically, SEM images of ZnO crystals grownunder laser power density of about 9.55 kW/cm² (FIG. 5a ), about 15.92kW/cm² (FIG. 5b ), about 22.29 kW/cm² (FIG. 5c ) and about 28.66 kW/cm²(FIG. 5d ) at about 200 kHz for about 5 min. All scale bars represent500 nm in length. FIG. 5e shows a schematic of crystal growth in kineticcontrolled and thermodynamic controlled processes (as marked in thecorresponding panels). Increasing the power from about 9.55 kW/cm² toabout 15.92 kW/cm², the energy barriers for growth of prismatic planes(m-planes) were overcome, resulted in a transformation from cylinder tohexagonal shape as shown from FIGS. 5a to 5b . It indicated that theenergy barriers of growth along <1011>, <1010> are overcome but not[0001] (c-axis). Therefore, the growth rate of 1101_11 planes is higherthan (0001), which results in a flat surface on the crystal tip. Whenthe pulsed laser power is increased to about 22.29 kW/cm², crystalswould grow along the preferred orientation of c-axis. These SEM imagesshow that energy barriers of growth of (0001) planes were overcome, sothat the growth rate of (0001) plans increased dramatically and ledcrystal to grow longer. As shown in FIGS. 5c and 5d , when the pulsedlaser power increased above 22.29 kW/cm², the tip did not grow smoothbut instead was bounded by hillocks which were composed of faces ofhigher Miller indices and tips of crystals tend to approach {1011}.Faces of hillocks have lower specific surface free energy than (0001),so that these higher Miller indices faces predominate. When the pulsedlaser power was above about 28.66 kW/cm², (0001) surface had the highestgrowth rate that leaded to a pyramid-like crystal structure. It is worthnoting that it is the peak power rather than the accumulated energy thatovercome the energy barriers. Evidence of this statement could be foundthat the certain morphology grown under specific high power-density thatwill not occur in the condition of irradiation by lower poweraccumulated for longer time, even though the total input energy is thesame. For example, the total irradiation energy by laser power densityof about 15.92 kW/cm² for 1.4 min is the same with about 22.29 kW/cm²irradiation for 1 min. However, the hillocks structure which indicatedthe activation of burst growth along [0001] direction, was not found inlaser condition of about 15.92 kW/cm², even when irradiated for 40 min.

As shown in the reaction in corresponding panels in FIG. 5e , two pathscould be identified by laser induced crystal growth. In kineticcontrolled path, the crystal is controlled by energy barriers of growthalong specific surfaces. The crystal growth is generally regarded as aprocess of 2D nucleation of island on the terraces followed by lateralmotion of steps. The 2D nucleation of island is similar to initialheterogeneous nucleation, in which the free energy barrier E, relates tosurface energy of specific plane,

$E \propto {\frac{\gamma^{3}}{\Delta \; G_{v}^{2}}.\mspace{14mu} \gamma}$

has different values along different planes. Surface energy of prismaticplanes {1010} is 1.15 J/m², and 1.37 J/m² for {1011} planes, and for thebasal plane surface (0001) is 2.0 J/m². Therefore, the energy barriersfor crystal growth of planes are in order of {0001}>{1011}>{1010}.Results from the actual reduction to practice showed that the occurrenceof crystal planes with increasing input energy followed the sequence of{1010}, {1011}, {0001}, which was in the same order of surface energyvalues cited above. When the input energy is not large enough toovercome the energy barriers of 2D nucleation on all crystal planes,then certain planes with low energy barriers will be formed first, andplanes with higher energy barriers not overcome will grow at a low rate.For example, when the input power is below about 22.29 kW/cm², largeenough to induced growth along <1011> but not enough to overcome theenergy barriers of 2D nucleation on (0001) surface, the crystal growthprocess is limited by kinetic factors of (0001), so that the growth rateof {10 1 1} is larger than (0001), and results in a hexagonal morphologywith a flat surface on the tip (as shown in FG. 5 b and illustrated inthe corresponding panel of FIG. 5e ). When the input energy increasesand is able to overcome the energy barriers of growth along all planes,the surface reaction is not the limiting factor and the growth of (0001)is no longer inhibited. In this circumstance, crystal growth willundergo a thermodynamic controlled pathway, as illustrated in reactionin the corresponding panel of FIG. 5e , where the product with largestGibbs energy ΔG will be preferred to form because it is the mostthermodynamic stable state. The Gibbs energy ΔG reaches maximum when thetotal surface energy ΣγA of crystal remains minimum as crystal grows. Itcould be measured by the increase of surface energy per volume dΣγA/dv.As calculated, dΣγA/dv is about 12.69 J/m in hexagonal structure andabout 10.63 J/m in a pyramid-like structure on crystal tip. Thepyramid-like structure is more stable than hexagonal structure inthermodynamic controlled reaction. Therefore, when the input energy ishigh enough (above about 28.66 kW/cm²), the ZnO crystal will have themorphology of the pyramid-like structure on the tip (as shown in FIG. 5d).

According to the present disclosure, nanomaterials could be deposited ina high rate controlled by pulsed laser. Using ZnO crystals as examples,(0001) planes (top surfaces) have higher growth rate than {0110} planes(cylindrical surfaces), and higher power-density results in highergrowth rate. Referring to FIG. 6a , SEM cross-sections images of nanorodcrystals grown under power density from about 9.55 to about 28.66 kW/cm²at 200 kHz for 5 mins are shown, with all scale bars representing 2 μm.Referring to FIG. 6b , corresponding graphs of length in nm and aspectratio of nanorod crystals vs. power density in kw/cm² are provided. ZnOcrystals grow into nanorods with different length. The anisotropicmorphology could be described by the aspect ratio, length/diameter(1/d), as shown in FIG. 6b . Increasing the laser power density from9.55 kW/cm² to 28.66 kW/cm², the length of ZnO crystals increases from1.09 to 4.49 μm, and the aspect ratio increase from 1.40 to 5.01.

According to one embodiment of the present disclosure, a route forpulsed laser synthesis of free-standing ZnO nanorod crystals, as shownin FIG. 7a and FIG. 7b , which presents an SEM image of ZnO crystalswith (0001) face up deposited on silicon substrate with/without anamorphous SiO₂ layer. Neither catalyst nor specific requirement ofsubstrate is needed. Accordingly, the process below is one example of alaser-pulsed methodology according to the present disclosure.

An exemplary controlled synthesis comprise steps of:

-   -   (1) Immersing a substrate in precursor solution containing        precursor reactants;    -   (2) Determining the laser input energy by stepped increasing        laser power density, when the deposition materials could be        detected or observed, set the condition as laser input energy        which just overcoming lowest Gibbs free energy barriers for        nucleation;    -   (3) Irradiate substrate with laser beam for a total irradiation        time with determined laser input energy to deposit initial        crystals (seeds);    -   (4) Immersing the substrate in precursor solution with a        different condition;    -   (5) Determining the laser input energy by stepped increasing        laser power density: when the color of nucleated crystals get        darker than original crystals (crystal size is detected larger),        set the condition as lower bound for input energy; when the net        deposition area is to become larger than original nucleated        crystal seeds area (additional nucleation start to occur outside        of existing crystals), set the condition as upper bound        condition for crystal growth;    -   (6) Irradiate initial crystals on substrate for a total        irradiation time based on desired crystal size, with determined        laser input energy between lower and upper bound to grow        following crystals.

Specific conditions in previous steps described above, for the case ofZnO presented, the precursor reactants are zinc chloride tohexamethylene tetramine (HMTA) (all chemicals from Sigma-Aldrich),concentration is about 15 mmol in step (1), laser power density isdetermined and applied as 19.1 kW/cm² in step (2) and (3). In step (3),the total irradiation time is 30s. In step (4), the precursor reactantsare the same with step (1) and precursor concentration is changed toabout 4 mmol. The minimum power density is determined as 9.55 kW/cm²,maximum power density is 31.84 kW/cm². The laser power density appliedin step (6) is at about 25.5 kW/cm², the total irradiation time is 2min. After growth, the substrate was rinsed with DI water and dry.

Those having ordinary skill in the art will recognize that numerousmodifications can be made to the specific implementations describedabove. The implementations should not be subjected to the particularlimitations described. Other implementations are possible.

For example, the present method can be modified to precisely produce allmaterials that can be chemically synthesized, which must follow thethermodynamics and kinetics of chemistry where Gibbs Energy Barriers arekey to determine the structures and morphology of a synthesizedmaterial. The proposed method can also be applied in a precursorsolution without a substrate. Various pulsed laser conditions can beused to search feasible conditions for satisfying the Gibbs energycondition without knowing beforehand the values of the respective GibbsEnergy Barriers. When a particular structure and morphology areidentified after using a laser condition, the condition is shown to be afeasible condition that can satisfy the respective Gibbs condition. Alaser condition is a combination of laser fluence, irradiation area,repetition rate, width (duration) of a pulse, and total time (or thetime for total number of pulses) for applying the laser condition. Thus,numerous laser conditions can be selected for achieving an intendedsynthesis for a structure/morphology. The substrate can also be modifiedto include many types of substrates including flexible substrates. Theprecursor condition includes precursor components, precursorconcentration and pH value.

1. A method of selectively controlling nucleation for crystallinecompound formation by pulsed energy source induced chemical synthesisand deposition, comprising: selecting a substrate and a precursorsolution, applying the selected precursor solution having a selectedcondition onto the substrate; and irradiating the substrate through theprecursor by a pulsed energy source with a predetermined input energy,thereby nucleating material seeds on the substrate.
 2. The method ofclaim 1, wherein the crystalline compound is chemically synthesized insolution.
 3. The method of claim 1, wherein the selected condition ofprecursor solution includes precursor components, precursorconcentration and pH value.
 4. The method of claim 1, wherein thesubstrate is one of rigid, flexible, or combination thereof adapted toabsorb the predetermined input energy.
 5. The method of claim 1, whereinthe pulsed energy source is pulsed laser.
 6. The method of claim 5,wherein the pulsed laser has defined laser conditions including pulseenergy, laser irradiation area, repetition rate, pulse width, total timeof pulsations, and combinations thereof.
 7. The method of claim 6,wherein the predetermined input energy of laser is determined byincreasing the laser condition in a stepped manner until precipitationoccurs.
 8. The method of claim 7, wherein applying the determined inputenergy from pulsed laser nucleates the crystal.
 9. A method ofselectively growing crystals, comprising: selecting a precursor solutionfor crystals growth, applying the selected precursor solution onto thesubstrate with nucleated crystal seeds; and irradiating the nucleatedcrystal seeds on substrate through the precursor by a pulsed energysource with a predetermined input energy.
 10. The method of claim 9,wherein the precursor solution conditions includes precursor components,precursor concentration and pH value.
 11. The method of claim 9, whereinthe pulsed energy source is pulsed laser.
 12. The method of claim 11,wherein the pulsed laser has defined laser conditions including pulseenergy, laser irradiation area, repetition rate, pulse width, total timeof pulsations, and combinations thereof.
 13. The method of claim 12,wherein the predetermined input energy of pulsed laser is between alower bound and an upper bound, in which the lower bound is determinedby increasing the laser condition in a stepped manner until a firstpredetermined crystal size is detected, and in which the upper bound isdetermined by increasing the laser condition in a stepped manner untiladditional nucleation occurs outside of the grown crystal.
 14. Themethod of claim 12, wherein the total pulsation time is selected basedon a desired size of the crystal.
 15. The method of claim 13, wherein afirst desired crystal morphology is grown isotropically by pulsed laserwith the predetermined input energy near and above the lower bound. 16.The method of claim 13, wherein a second crystal morphology is grownanisotropically by pulsed laser with the predetermined input energy nearand below the upper bound.